• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.1
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• pp.119-128
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• 2017

G-induced Loss of Consciousness(G-LOC) can be predicted by measuring Electromyogram(EMG) signals. Existing studies have mainly focused on specific body parts and lacked of consideration with quantitative EMG indices. The purpose of this study is to analyze the indices of EMG signals by human body parts for monitoring G-LOC condition. The data of seven EMG features such as Root Mean Square(RMS), Integrated Absolute Value(IAV), and Mean Absolute Value(MAV) for reflecting muscle contraction and Slope Sign Changes(SSC), Waveform Length (WL), Zero Crossing(ZC), and Median Frequency(MF) for representing muscle contraction and fatigue was retrieved from high G-training on a human centrifuge simulator. A total of 19 trainees out of 47 trainees of the Korean Air Force fell into G-LOC condition during the training in attaching EMG sensor to three body parts(neck, abdomen, calf). IAV, MAV, WL, and ZC under condition after G-LOC were decreased by 17 %, 17 %, 18 %, and 4 % comparing to those under condition before G-LOC respectively. Also, RMS, IAV, MAV, and WL in neck part under condition after G-LOC were higher than those under condition before G-LOC; while, those in abdomen and calf part lower. This study suggest that measurement of IAV and WL by attaching EMG sensor to calf part may be optimal for predicting G-LOC.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.1
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• pp.37-42
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• 2012

The aim of the present study was to elucidate the direct effects of melatonin on bladder activity and to determine the mechanisms responsible for the detrusor activity of melatonin in the isolated rat bladder. We evaluated the effects of melatonin on the contractions induced by phenylephrine (PE), acetylcholine (ACh), bethanechol (BCh), KCl, and electrical field stimulation (EFS) in 20 detrusor smooth muscle samples from Sprague-Dawley rats. To determine the mechanisms underlying the inhibitory responses to melatonin, melatonin-pretreated muscle strips were exposed to a calcium channel antagonist (verapamil), three potassium channel blockers [tetraethyl ammonium (TEA), 4-aminopyridine (4-AP), and glibenclamide], a direct voltage-dependent calcium channel opener (Bay K 8644), and a specific calcium/calmodulin-dependent kinase II (CaMKII) inhibitor (KN-93). Melatonin pretreatment ($10^{-8}{\sim}10^{-6}M$) decreased the contractile responses induced by PE ($10^{-9}{\sim}10^{-4}M$) and Ach ($10^{-9}{\sim}10^{-4}M$) in a dose-dependent manner. Melatonin ($10^{-7}M$) also blocked contraction induced by high KCl ($[KCl]_{ECF}$; 35 mM, 70 mM, 105 mM, and 140 mM) and EFS. Melatonin ($10^{-7}M$) potentiated the relaxation response of the strips by verapamil, but other potassium channel blockers did not change melatonin activity. Melatonin pretreatment significantly decreased contractile responses induced by Bay K 8644 ($10^{-11}{\sim}10^{-7}M$). KN-93 enhanced melatonin-induced relaxation. The present results suggest that melatonin can inhibit bladder smooth muscle contraction through a voltage-dependent, calcium-antagonistic mechanism and through the inhibition of the calmodulin/CaMKII system.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.5
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• pp.377-381
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• 2014

Propofol is a widely used anesthetic. Many studies have shown that propofol has direct effects on blood vessels, but the precise mechanism is not fully understood. Secondary intrapulmonary artery rings from male rats were prepared and mounted in a Multi Myograph System. The following constrictors were used to induce contractions in isolated artery rings: high $K^+$ solution (60 mmol/L); U46619 solution (100 nmol/L); 5-hydroxytryptamine (5-HT; $3{\mu}mol/L$); or phenylephrine (Phe; $1{\mu}mol/L$). The relaxation effects of propofol were tested on high $K^+$ or U46619 precontracted rings. Propofol also was added to induce relaxation of rings preconstricted by U46619 after pretreatment with the nitric oxide synthase inhibitor $N^G$-nitro-L-arginine methyl ester (L-NAME). The effects of propofol on $Ca^{2+}$ influx via the L-type $Ca^{2+}$ channels were evaluated by examining contraction-dependent responses to $CaCl_2$ in the absence or presence of propofol (10 to $300{\mu}mol/L$). High $K^+$ solution and U46619 induced remarkable contractions of the rings, whereas contractions induced by 5-HT and Phe were weak. Propofol induced dose-dependent relaxation of artery rings precontracted by the high $K^+$ solution. Propofol also induced relaxation of rings precontracted by U46619 in an endothelium-independent way. Propofol at different concentrations significantly inhibited the $Ca^{2+}$-induced contractions of pulmonary rings exposed to high $K^+$-containing and $Ca^{2+}$-free solution in a dose-dependent manner. Propofol relaxed vessels precontracted by the high $K^+$ solution and U46619 in an endothelium-independent way. The mechanism for this effect may involve inhibition of calcium influx through voltage-operated calcium channels (VOCCs) and receptor-operated calcium channels (ROCCs).

• The Korean Journal of Pharmacology
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• v.28 no.1
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• pp.75-79
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• 1992

Higenamine, which is one of active component of Aconiti tuber, has been known to have positive inotropic effect through adrenergic beta-receptor. The effect of higenamine on norepinepharine or potassium induced contraction of pulmonary aorta in rabbit were studies. 1. The contraction of aortic strips induced by norepinephrine was suppressec by pre-or post-treatment of higenamine dose dependently and those effects of higenamine were prevented by propranolol. The $pA_2$ value of higenamine against propranolol calculated as 8.25. 2. The effect of higenamine was not affected by phentolamine. 3. Isoprotrenol has shown 10 times stronger vasodiatory effect on norepinephrine induced cntracture than that of higenamine but high concentration $(3.3{\times}10^{-6}\;M)$ of isoproterenol produce intrinsic activity. 4. Vasodilatory effect of higenamine or isoproterenol was not observed in potassium induced contacture of pulmonary aortic strips. These results strongly suggest that higenamine dilated the pulmonary vascular smooth muscle through stimulation of adrenergic beta-receptor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.184-192
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• 1998

This paper deals with an extended analytical solution for the mixture solidification problem, in which temperature is inherently coupled with the solute transport due to the presence of volume contraction induced flow. A new exact solution to the energy equation accounting for the convection effect in the melt is successfully derived, which allows the present analysis to cover a high initial superheating. Difference in properties between the solid and liquid phases is rigorously incorporated into the model equations in the solid fraction weighted form. Taking advantage of linearized correction factors, a systematic and easy-to-implement algorithm for determining the solidus and liquidus positions is introduced, which proves not only to converge stably but also to be very efficient. For a specific case, the present results show excellent agreements with the existing solution. The effect of convection in the melt becomes appreciable with increasing the initial superheating. It is revealed that variable properties in the mushy region significantly affect the solidification behaviors. The present study is also capable of resolving the interaction between microsegregation and macrosegregation.

• Journal of Pharmaceutical Investigation
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• v.14 no.2
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• pp.86-91
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• 1984

A ginseng preparation (GP) consisting of ginseng ex., lycium fructus ex., four kinds of vitamines and caffein was evaluated for acute toxicity and general pharmacology. Average lethal doses $(LD_{50})$ of GP in male mice were 2,988mg/kg (i.p.) and more than 3g/kg (p.o.). In dosage of 300 and 900mg/kg (p.o.) showed no analgesic activity in both tests of the writhing method induced by acetic acid and of tail pressure method and no effect on the pentetrazole-induced convulsion. However, it appeared to have a hypothermic action only in dose of 900mg/kg. The duration of hypnosis induced by hexobarbital sodium in mice was shortened by GP, being probably due to caffein. GP Produced no marked contraction of isolated ileum and uterus in high concentrations of up to $1{\pm}10^{-3}g/ml$. These results suggested that GP did not show any considerable central nervous depressant activity and exhibited very weak actue toxicity in mice.

• The Korean Journal of Physiology
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• v.30 no.1
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• pp.11-20
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• 1996

To investigate the properties of cromakalim-opened $K^{+}\;channels$ in aorta of spontaneously hypertensive rats (SHR), the effect of cromakalim on tension was compared in endothelium-rubbed aortic rings from SHR and normotensive Wistar-Kyoto rats (WKY). 1. Cromakalim relaxed the aortic ring contracted by $10^{-7}$ M norepinephrine (NE) dose-dependently, and this relaxant response to cromakalim was blocked by $10^{-5}$ M glybenclamide. 2. Cromakalim also relaxed the contraction induced by high $K^{+}$-solution or 10 mM tetraethylammonium dose-dependently. However, the relaxant response to cromakalim was decreased by raising the $K^{+}$ concentration. 3. SHR aorta exhibited myogenic tone in resting state which was inhibited by cromakalim, verapamil or $Ca^{2+}-free\;PSS.$ Whereas, WKY aorta did not exhibit any myogenic tone in resting state. 4. When aortic rings from both strains were contracted by $20\;mM\;K^{+}\;or\;NE$, relaxant responses to low concentration of cromakalim $(below\;10^{-7}\;M)$ were not different between WKY and SHR, but maximum relaxant response to cromakalim $(above\;3{\times}10^{-7} \;M)$ was greater in SHR than in WKY. 5. When the relaxant response to cromakalim was expressed as percent of maximum relaxation induced by $Ca^{2+}-free\;PSS$, relaxant response to cromakalim in 20 mM $K^{+}-induced$ contraction was not different between WKY and SHR. From the above result, it is suggested that relaxant responses to cromakalim are greater in SHR than WKY, and this may be due to the myogenic tone of aortic rings from SHR.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.5
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• pp.297-303
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• 2012

This study was designed to elucidate high $K^+$-induced relaxation in the human gastric fundus. Circular smooth muscle from the human gastric fundus greater curvature showed stretch-dependent high $K^+$ (50 mM)-induced contractions. However, longitudinal smooth muscle produced stretch-dependent high $K^+$-induced relaxation. We investigated several relaxation mechanisms to understand the reason for the discrepancy. Protein kinase inhibitors such as KT 5823 (1 ${\mu}M$) and KT 5720 (1 ${\mu}M$) which block protein kinases (PKG and PKA) had no effect on high $K^+$-induced relaxation. $K^+$ channel blockers except 4-aminopyridine (4-AP), a voltage-dependent $K^+$ channel ($K_V$) blocker, did not affect high $K^+$ -induced relaxation. However, N(G)-nitro-L-arginine and 1H-(1,2,4)oxadiazolo (4,3-A)quinoxalin-1-one, an inhibitors of soluble guanylate cyclase (sGC) and 4-AP inhibited relaxation and reversed relaxation to contraction. High $K^+$-induced relaxation of the human gastric fundus was observed only in the longitudinal muscles from the greater curvature. These data suggest that the longitudinal muscle of the human gastric fundus greater curvature produced high $K^+$-induced relaxation that was activated by the nitric oxide/sGC pathway through a $K_V$ channel-dependent mechanism.

• The Journal of Korean Physical Therapy
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• v.20 no.1
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• pp.1-9
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• 2008

Purpose: This study examined the effects of pre-eccentric exercise to the quadriceps for the prevention of delayed onset muscle soreness (DOMS) and recovery of muscular function, depending on the training intensities. Methods: Subjects were divided into one of three groups that control group, a low intensity eccentric exercise group (LIEE group) and a high intensity eccentric exercise group (HIEE group). Subjects who underwent pre-eccentric exercise undertook exercise at an intensity of 25% and 75% of maximal voluntary contractions, respectively. After undertaking pre-eccentric exercise for eight weeks, eccentric exercise was applied again to induce DOMS. Measurements were conducted to examine pain and muscular function changes before, immediately after, after the induction of DOMS, and at the first, third, fifth and seventh days after the induction of DOMS. Results: Subjects who underwent pre-eccentric exercise showed a significant difference from the control group for the changes in the visual analogue scale (VAS) pain threshold, pressure pain threshold and muscle thickness by isometric contraction from measuring DOMS, and in particular, pain threshold by isometric contraction had remarkable effect in the LIEE group of subjects. For the change of the root mean square values using mechanomyography (MMG) as the measurement of muscular function recovery, subjects who had undertaken pre-eccentric exercise group showed a significant difference as compared to the control group. Conclusion: Pre-eccentric exercise was very effective in preventing and recovering delayed onset muscle soreness and was helpful to prevent and recover from decreased muscular function. The difference based on the intensity of exercise was not great, but it was more effective in the low intensity eccentric exercise group of subjects. Therefore, it can be considered that pre-eccentric exercise has a high application value as a physical therapy intervention for prevention and rehabilitation of sports injuries.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.415-421
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• 2003

It is now generally accepted that acupuncture is effective in diarrhea caused by bacterial infection. However, its effect on the intestinal smooth muscle dysfunction is not clear. Therefore, we investigated the effect of acupuncture therapy at Jiao-chao (GV-1) on the intestinal muscle dysfunction in weaning piglets orally infected by Escherichia coli. The animals are divided into four groups; 1) E. coli + no-treatment, 2) E. coli + antibiotic, 3) E. coli + acupuncture, 4) normal group. In the three E. coli infected groups, low frequency electrical field stimulation (EFS, 1 Hz) provoked triphasic responses composed of initial relaxation followed by on-contraction and off-contraction. While in the normal group, EFS (1Hz) induced biphasic responses composed of relaxation during the stimulation and off-contraction. At the high frequency (16Hz) EFS, both on-contraction and off-contraction of the E. coli + antibiotic, E. coli + acupuncture and the normal group were larger than those of the E. coli + no-treatment group. In the non-adrenergic non-cholinergic (NANC) condition, only biphasic responses occurred to EFS in all experimental groups and the off-contraction of E. coli + antibiotic, E. coli + acupuncture and the normal group were larger than those of the E. coli + no-treatment group. The response to carbachol of those three groups was also significantly greater than that of the E. coli + no-treatment group. These results suggest that acupuncture is as effective as antibiotic in the dysfunction of colonic circular muscle caused by E. coli infection. The maintenance of contractile neuromuscular transmission seems to be involved in the mechanism of the acupuncture effects on diarrhea.